SK 720 and MKS servos...

[HSC]

Hello !

I plane to buy MKS HBL 960/990 for my heli.
Do I need too plug in some Skokum bus, or I can pluge direct in SK 720...
Since this are high power servos...
Regards

[gitbse]

Is it the older Blue or the new Black? The blue would do well to use a Sbus, but it's completely unnecessary with the newer generation 720black.

[HSC]

Black720..., but I have 540 too what about 540, this one will handled too direct ?
Thanx, regards

[georgi UK]

=] SK max rate their units at 10vdc, this is 2vdc less than the actual spec, so there is plenty of margin when using a 2S supply / high draw servo setup.

[gitbse]

Yea, black will be fine. I run Savox HV's which pull ALOT of juice running a straight 2 cell. No problems.
You should have two open slots, just split the battery lead into a Y harness, and plug two power leads into the ESC. That will help with higher current because servo leads are technically only "rated" at 5 amps each.

[jsbach#1]

What about keeping the heavy guage hv servo wiring away from the 720 black ?

[Luvmyhelis]

Originally Posted by jsbach#1

What about keeping the heavy guage hv servo wiring away from the 720 black ?

It won't be any issue whatsoever. I run a set of those with my own Sk720. Do make sure you either run two leads up from the separate rx pack or a thicker lead through most the run before you split them to introduce them into the Sk720 servo bus. Use the SwashA and IOB slots to spread out the input amperage. It isn't just Skookum, no fbl controller out there can really handle more than 10amps through any single servo bus due to how small the pins are. As far as the heavier servo wires go, just make sure to either curl or angle them so they aren't coming into the Sk720 straight, that way vibes tend to bleed off before coming into the pin bus. Straight wires , tight wires, also short wires connected to any frame part transmit vibes.

[omerco]

Originally Posted by gitbse

Yea, black will be fine. I run Savox HV's which pull ALOT of juice running a straight 2 cell. No problems.
You should have two open slots, just split the battery lead into a Y harness, and plug two power leads into the ESC. That will help with higher current because servo leads are technically only "rated" at 5 amps each.

I reccomand NOT using a Y harness - that was the reason i got my reset: in time the connections deteriorated and caused the voltage to drop. And as said - every servo connection is a bottle neck as it is.

+1 for LMH: thick lead from the battery devided to 2 or 3 servo leads closer to the gyro, with a good connector between the first and bat (i use EC3). If you lack a free port for the Backup solder a female servo wire along with the 2 other male ones.

[gitbse]

Originally Posted by omerco

I reccomand NOT using a Y harness - that was the reason i got my reset: in time the connections deteriorated and caused the voltage to drop. And as said - every servo connection is a bottle neck as it is.

+1 for LMH: thick lead from the battery devided to 2 or 3 servo leads closer to the gyro, with a good connector between the first and bat (i use EC3). If you lack a free port for the Backup solder a female servo wire along with the 2 other male ones.

Not to argue, but how is that different from what I described? I'd like to know, because I would like mine setup as flawlessly as I can... just having a bec fail mid 100' inverted two weeks ago.

[jsbach#1]

Which BEC failed ? I have run a 2s lipo till now but I'm sick of it, was going to run a western bec in both birds, no back up no nothing, nice and clean.

[gitbse]

Castle pro. I had one about two years ago blow up, frying my entire electronic setup in my 600, and then two weeks ago it decided to kill my 700. No more bec for me, straight 2s from now on. One less line in the chain to fail.

I would love a western robotics, but not in the budget.

[Fruitbat]

I thought the SK powerbus was the solution for these issues?
I am in the process of installing one on my new Logo 700, so if I am wrong please let me know!
Thanks
Dave

[gitbse]

Originally Posted by georgi UK

=] SK max rate their units at 10vdc, this is 2vdc less than the actual spec, so there is plenty of margin when using a 2S supply / high draw servo setup.

Like said earlier, no bus is needed. We are just discussing refining details.

[omerco]

Originally Posted by gitbse

Not to argue, but how is that different from what I described? I'd like to know, because I would like mine setup as flawlessly as I can... just having a bec fail mid 100' inverted two weeks ago.

Sorry i might have misunderstood you - i thought you meant classic Y harnesd: one male servo connector and 2 females. If you meant soldered Y than we meant the same.

For the BEC, and Castle's especially - i lost an x7 4 months back with the castle pro failing on me - 1000$ damage.
Do yourself s favor and stay 2s, and if you insist than WR is the only proper option i know of.

[jsbach#1]

hmmmmm

[gitbse]

Originally Posted by omerco

Sorry i might have misunderstood you - i thought you meant classic Y harnesd: one mail servo connectors and 2 females. If you meant soldered Y than we meant the same.

For the BEC, and Castle's especially - i lost an x7 4 months back with the castle pro failing on me - 1000$ damage.
Do yourself s favor and stay 2s, and if you insist than WR is the only proper option i know of.

Ok, then yes we are on the same page.

[Luvmyhelis]

I have had a couple Castle bec's go poof on me also running off the main packs. But never since going to the separate 3s flight packs. I have three out flying now in 600s off 3s Rx packs with other guys that have flown hundreds of flights without fail. The Herc is a great bec, as are the Gryphon's. And Scott Gray Reactors. Again, I have run the Herc and Gryphons off both 6 and 12s. But went to separate 3s Rx packs almost two years ago with all them. Heat from the high to lower voltage step down is what stresses any and all bec's. Lower the initial voltage supply, and you seriously lower the stress on the bec. I have had zero, and I do mean zero issues since doing the 3s Rx bec changeover.

This last month due to a change in circumstances, and input from a horde of others using 2s rx packs. I rewired my 600 that is equipped with the new HV Turnigy/ Kst rebranded servos. And continually saw my new 2s 1800 65c Rx pack go well below 7v warning levels all throughout the flights with my Jeti telemetry. So when I can afford it, I am going back to equipping it with a separate bec running off a 3s Rx pack once again.